Two operational procedures (be them preparations, measurements or transformations) are said to be operationally equivalent if they cannot be distinguished by any experiment. Noncontextuality, in the generalized form introduced in [1]}, is a restriction to ontological models requiring that if two procedures are operationally equivalent, they must be represented by the same object in the ontological model. This notion can be seen as an extension of the traditional one of Kochen-Specker [2]}, [1]}.
